I might have a temporary solution
I had a similar problem with the barriere not loading, so i placed several teleporters with Movement Modifier where the barrieres are (Picture 1) and one teleporter on the Player Spawner, so that the player is teleported directly to the next teleporter when he spawns (Picture 2) and in the end the player gets teleportet to the start of the map. In my case this happens so fast that the player is already there where he shold be, when he is joining the map and the barrieres are all loaded in
(I also used the setting from AtAshTag)
I hope this helps you too